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Thursday, 15 June 2017

Implementation period (step-wise)

From an epidemiological perspective implementation entails more than simply carrying out the screening
process and onward referral for assessment whenever required. The particular epidemiological
concerns at the early, implementation phase focus on the complete and accurate recording of all indi-vidual data pertaining to every participant, the screening test, its result, the decisions made as a consequence
and their eventual outcome in terms of diagnosis and treatment and monitoring the causes
of death.

Pilot demonstration projects have been carried out in some European countries to assess the feasibility
of national programmes and their impact on routine services and to test whether the short-term
outcomes of RCTs could be achieved in a context of routine care by a programme covering the whole
target population (UK Colorectal Cancer Screening Pilot Group 2004; Goulard et al. 2008).

A new screening programme should be implemented in such a way that effectiveness can be evaluated.
This can be achieved using individual-level randomisation into screening and control groups at
the phase when the programme is new and resources and practical limitations prohibit the full coverage
of the target population. This step-wise implementation, in which the target population is gradually
taken into the programme as available resources expand, is both feasible and accepted when the
available resources are used to their full extent.

A randomised screening design is helpful in the start-up phase when all the healthcare services and
the infrastructure have not been evaluated within the screening programme, and since there cannot
be certainty that the desired outcome and quality will be reached in that particular programme. In the
first years of screening, an invitation scheme that gradually expands to cover more regions and age
groups over the years can be used. Individuals in the control group will be offered screening later after
the first years. This provides an unbiased comparison group.

A model from Finland is based on individual-level randomisation over the first six years (Malila, Anttila
& Hakama 2005). For a six-year implementation phase it was expected that the number of colorectal
cancer deaths will accumulate during 10 years from launching the programme in a population of
around 3 million and a colorectal cancer mortality rate of approximately 15/100 000. Meanwhile, feasibility
can be studied and the programme monitored with various process indicators such as attendance
rates, proportion of test positives, detection rates, and positive predictive values.

A randomised screening design can also be used to assess the impact of alternative policies, such as
different methods of invitation, or different target age groups. The randomised approach may also
represent an acceptable and feasible alternative to assess the impact of a new screening test or to
compare cost-effectiveness of different screening strategies, when a clinical randomised trial to evaluate
the reduction in cancer occurrence or mortality is deemed impractical.

Recommendation

Ideally, any new screening programme should be implemented using individual-level randomisation
into screening and control groups in the phase when resources and practical limitations prohibit
the full coverage of the target population (VI - A).